There are many devices in use in easily portable card form, such as company, student, or organization ID cards and licenses that bear personal information including images such as portraits of the bearer and text and symbols such as the name and affiliation of the bearer. There are also many cards such as automated teller machine cards, credit cards, and other bank cards with these same characteristics for which security is an important concern and which bear images such as portraits of the bearer and personal information in text and symbols. Most of these cards are covered with a transparent protective overlay.
This applies to cards, but also to many other products. To meet demands on the part of users (who want to be able to get good quality products quickly) and suppliers (who want to be able to produce these cards most profitably), it is extremely important to supply products at low cost and in short periods of time by achieving high productivity by producing mass quantities of product faster and with a higher rate of good products.
For image information or information composed of text and symbols recorded on a card surface, various well known methods have already been proposed for techniques to inspect the recording quality (print quality) and techniques to inspect whether the contents that are recorded on the card match the images, text, or symbols that were supposed to be printed on the card surface. Such well known methods do not inspect transparent protective overlays. Two such examples are Utility Model Announcement H02 (1990)-144448 (Omura, et al., "Card Text and Image Printing Device," Japan, Utility Model Registration Application) and U.S. Pat. No. 5,646,388 (D'Entremont, et al., "Systems and Method for Recording Data," USA, Patent Application, patent families WO 9610798 and AU 9538267). Both of these methods send a card recorded with the images, text, or symbols on the card surface whose card surface images, text, or symbols are to be inspected to an inspection stage by means of a card conveyor mechanism. An inspection light is then shone on the area to be inspected on the card, the reflected light thus obtained is picked up by a means of inspection such as a CCD, and data from the reflected light received is data processed to determine whether the card, not including the transparent protective layer, is good.
Ideal quality for a transparent protective overlay is generally determined by several factors: is it of uniform thickness, is it formed only where intended, and are outlines sharp in the viewed area. In practice, however, they may not be ideally formed. Some of the possible causes include the obvious, such as the method of forming the transparent protective overlay or the conditions, as well as possibilities such as the layer structure of the transparent protective overlay (material and structure), the material of the object the layer is formed on, and problems of physical compatibility caused by the relationship between the states of the surfaces involved. Some examples of poor quality include transparent protective overlays that are formed unevenly, areas where transparent protective overlay should be formed but isn't, transparent protective overlay that is formed in areas where it is not necessary (flash and misalignment of transfers), damage to the transparent protective overlay formed, and air bubbles formed between the object surface and its transparent protective overlay. These problems may be fewer or greater, but statistically speaking, they always appear to some degree.
For cards on which recorded images, text, and symbols are protected by a transparent protective overlay, it is very important that quality control of the transparent protective overlay be performed highly efficiently if demands for supplying large quantities at low cost in short periods, as described previously, are to be met.
As things stand now, conventional inspections determine if transparent protective overlays placed on cards to protect images, text, or symbols recorded by printing or the like under the systems currently in widespread use meet quality standards relies solely on a visual inspection of the transparent protective overlay by a trained inspector. Under current practice, the inspection is dependent on this person.
This conventional system has problems of nonuniform application of inspection standards, since inspectors will vary in terms of skill, their physical or mental condition may vary on any given day, and the transparency of the film makes inspection difficult. There is also an upper limit to how many units can be inspected in a given period of time so that further improvements are unattainable.